. >> biden tuesday voicing concern over china's aggressive new air defense identification zone in the east chinese sea. this included more than five hours of face-to-face meetings with chinese president xi jinping who showed no sign of backing down from his exercise to gain control over japan's senkaku islands. let's give viewers a sense of why americans should care about this dispute over some islands in the east china sea. >> i think they should care because it looks as though that area is becoming destabilized. you have china, its tension with japan, with countries in the south china sea, indonesia, the philippines. they are using their muscle to try to push their rule over those waters. these countries are going to push back. you've got a very tense situation down there. historically in the entire post war period the united states has, shall we say, had the back of countries like japan and south korea. and at this moment, they literally are explicitly doubting that. that's why vice president biden has to go out there, to reassure them. i have no recollection of a u.s. administrati